The IRS collected more than $7 billion in employment tax penalties in a recent fiscal year — and a disproportionate share came from small businesses that simply didn't know what they were doing wrong. Payroll looks straightforward on the surface: pay your people, send taxes to the government, repeat. But the details buried in that process — deposit schedules, withholding calculations, filing deadlines, worker classifications — are where costly mistakes hide. If you run a small business and handle payroll in-house, this guide is your early warning system.

Misclassifying Workers as Independent Contractors

One of the most expensive payroll compliance mistakes a business owner can make is treating an employee as a 1099 independent contractor. The IRS uses a multi-factor behavioral and financial control test to determine worker status, and getting it wrong means you could owe back payroll taxes, unpaid employer contributions, and substantial penalties — sometimes stretching back years.

The core question isn't what you call the relationship; it's how much control you exercise over when, where, and how the work gets done. If you set someone's schedule, provide their tools, and direct their daily tasks, the IRS will likely view that person as an employee regardless of what your contract says. Review every contractor relationship at least annually, and when in doubt, consult a payroll compliance professional before a classification audit forces the issue.

Missing Payroll Tax Deposit Deadlines

Federal payroll tax deposits aren't optional, and they aren't forgiving. The IRS assigns employers to either a monthly or semi-weekly deposit schedule based on lookback period tax liability, and missing those deadlines triggers a penalty that escalates the longer you wait — from 2% for deposits one to five days late all the way up to 15% for amounts still unpaid more than ten days after an IRS notice.

Many small business owners don't realize their deposit schedule can change from year to year, or that a single large payroll can push them into a more frequent schedule mid-year. Set calendar alerts, automate deposits through your payroll system, and reconcile your tax liability after every payroll run. Payroll processing errors in this area are almost always preventable with the right system and habits in place.

Incorrect Withholding Calculations

Withholding too little — or too much — from employee paychecks creates downstream problems for everyone. Employees who are under-withheld may face surprise tax bills in April, damaging morale and trust. Over-withheld employees are essentially giving the government an interest-free loan. Either way, inaccurate payroll withholding can trigger IRS notices and accuracy-related penalties if the discrepancies are significant.

Common causes include:

  • Failing to update withholding after an employee submits a new W-4
  • Applying the wrong federal or state tax tables after annual updates
  • Mishandling supplemental wages like bonuses, commissions, or severance
  • Ignoring state and local income tax withholding requirements for remote employees

Make it standard practice to audit your tax tables at the start of each calendar year and any time an employee changes their withholding elections.

Failing to Keep Accurate Payroll Records

The IRS and Department of Labor both require employers to retain payroll records — and the rules aren't identical. Federal law generally requires keeping payroll tax records for at least four years from the date the tax was due or paid. FLSA wage and hour records must be retained for at least three years. State requirements can extend these timelines further.

Incomplete or disorganized records don't just create audit risk; they make it nearly impossible to defend yourself if an employee files a wage claim or the IRS questions a filing. Accurate payroll records should include hours worked, gross wages, tax withholdings, pay dates, benefit deductions, and copies of all filed returns. If your recordkeeping is living in spreadsheets and email threads, that's a liability waiting to surface.

Filing Payroll Tax Returns Late or Incorrectly

Even if you deposit taxes on time, failing to file Form 941 (the quarterly federal payroll tax return) by its deadline — or filing it with errors — adds another layer of penalties. A failure-to-file penalty starts at 5% of unpaid taxes per month, up to 25%. Errors on the return itself can trigger IRS correspondence audits that consume hours of your time and may require costly amendments.

Common filing mistakes include transposing EIN numbers, miscalculating total tax liability, and forgetting to account for third-party sick pay or employer health coverage contributions. Annual reconciliation between your W-2s and your 941s is a critical check that many small businesses skip — and the IRS doesn't.

Let Nomad Partners Handle the Details

Payroll compliance isn't a set-it-and-forget-it function. Tax rules change, employee situations evolve, and the margin for error is thin. At Nomad Partners, we manage payroll administration end to end — from accurate withholding and timely tax deposits to recordkeeping and quarterly filings — so you're never one missed deadline away from an IRS penalty.

Talk to our team today and find out how we can take payroll off your plate and keep your business on the right side of compliance.